Detailed Explanation of the Conditions of Application of Different Types of Control Valves

●  Straight through single seat valve

Generally applicable to the process requirements of small leakage, small flow, the valve before and after the pressure difference is small occasions. However, valves with an aperture of less than 20 mm are also widely used for occasions with larger differential pressures.

Not suitable for high viscosity or containing suspended particles fluid occasions.

●  Through double-seat valve

Generally applicable to the leakage requirements are not strict, the flow rate and the valve before and after the pressure difference is large occasions.

But not suitable for high viscosity or containing suspended particles fluid occasions.

●  Sleeve valve

Generally suitable for fluid clean, does not contain solid particles occasions.

Before and after the valve pressure difference is large and the liquid may appear flash or cavitation occasions.

●  Ball valve

Suitable for high viscosity, containing fibres, granular and dirty fluids.

Adjustment system requires a wide range of adjustable (R up to 200:1; 300:1) occasions.

When the seat gasket is made of soft material, it is suitable for applications requiring a tight seal.

The "O" type ball valve is generally applicable to the occasion of two-position cut-off.

"V" type ball valve is generally applicable to continuous adjustment system, its flow characteristics approximate to equal percentage.

●  Angle type valve

Generally suitable for the following applications.

High viscosity or suspended fluids (if necessary, can be connected to the flushing liquid pipe).

fluids in mixed gas-liquid phase or prone to flash vapour.

The pipeline requires right-angle piping occasions.

●  High pressure angle valve

In addition to the various occasions in 5), also suitable for high static pressure, large differential pressure occasions. But must be a reasonable choice of materials and structure of the valve parts in order to extend the service life.

●  valve body separation type adjustment valve

Generally suitable for high viscosity, containing particles, crystallization and fiber fluid occasions.

For strong acid, strong alkali or strong corrosive fluid occasions, the valve body should be selected with corrosion-resistant lining, valve cover, spool and valve seat should be used corrosion-resistant pressure pad or the corresponding corrosion-resistant materials. Its flow characteristics are better than diaphragm valves.

●  Eccentric rotary valve

Suitable for larger flow capacity, adjustable than wide (R up to 50:1 or 100:1) and large differential pressure, tight seal occasions.

●  butterfly valve

Suitable for large diameter, large flow and low pressure differential occasions.

Generally suitable for thick turbid liquid and fluid containing suspended particles occasions.

For occasions requiring tight sealing, rubber or PTFE soft sealing structure should be used; for corrosive fluids, the corresponding corrosion-resistant lining needs to be used.

●  Three-way valve

For fluid temperature of 300 ℃ below the diversion and merging occasions, for simple proportioning adjustment. The temperature difference between the two fluids should not be greater than 150℃.

●  Diaphragm valve

Suitable for strong corrosion, high viscosity or fluid containing suspended particles and fibres, while the flow characteristics of the occasion does not require strict. Due to the restrictions of the diaphragm lining, can only be used for pressure less than or equal to 1MPa, the operating temperature is less than 150 ℃ occasions.

●  Bellows seal valve

Suitable for vacuum systems and fluids for highly toxic, volatile and rare and valuable fluids.

●  Low temperature control valve

Suitable for low temperature working conditions and deep freezing occasions.

Media temperature in -100 ~ 40 ℃, optional with heat sink (here for heat absorption) plus flexible graphite packing valve.

When the medium temperature is -200 ~ -100℃, long neck type low temperature valve is suitable.

●  low S-value energy-saving adjustment valve

Suitable for process load changes or when the S value is less than 0.3 occasions.

●  Low noise valve

Suitable for liquid flash, cavitation and gas in the valve shrinkage surface flow rate greater than the speed of sound and the predicted noise more than 95dB (A) occasions.

●  Fast shut-off valve

Suitable for two-position regulating system and process failure, the valve needs to be opened or closed in an emergency situation.

●  Self-operated regulating valve

Suitable for small changes in flow, regulation accuracy requirements are not high or instrumentation gas supply difficulties in the occasion.

Special process production process, should be based on the use of experience in the selection of special regulating valve.